1. Field of the Invention
This invention relates to a wraparound, heat-recoverable fabric sleeve for enclosing an elongate object, such as a pipe or a cable, or joints or splices between pipes or cables. In particular the invention relates to such a wraparound sleeve, having longitudinal edges which overlap to close the wraparound.
2. Introduction to the Invention
Heat recoverable articles are well known. They are articles whose dimensional configuration may be made to change when subjected to an appropriate treatment. Typically heat recoverable articles comprise a heat shrinkable sleeve made from a polymeric material that exhibits the property of elastic or plastic memory as described, for example in U.S. Pat. Nos. 2,027,962, 3,086,242 and 3,597,372. More recently heat recoverable articles comprising fabrics have become known, as described for example in EP-A-0116393 (MP0790) and EP-A-0117026 (RK176) and EP-A-0116392 (RK178). These comprise a recoverable fabric in conjunction with a polymeric matrix formed by laminating a polymeric material to one or both sides of the fabric to render it impervious.
Wraparound heat-recoverable sleeves for enclosing elongate objects are also well known. They typically comprise a sheet of material which is wrapped around the object, and then the longitudinal edges held together in some way to close the wraparound to form a tubular article. In some known wraparound sleeves the longitudinal edges overlap. They may then be secured together by bonding e.g. by adhesive, by fusion or by a penetrating closure such as stitching or riveting. Where the longitudinal edges overlap in this way an additional patch closure strip may be used, bonded over the overlapped edges. Again the bond between the patch and each of the overlapped edges may be by adhesive, by fusion or by a penetrating closure means. The bond between the patch on each of the overlapped edges may be instead of, but is usually additional to, the bond between the overlapped edges themselves. Other types of closure are also known for wraparound sleeves. One common closure, known as a "rail and channel" closure, comprises forming the longitudinal edges of the sleeve into upstanding rails, and providing a channel which slides over the rails to hold the wraparound article closed. Typically the "rail and channel" closure and other similar mechanical-type closures can withstand significantly higher recovery forces than the overlapped and patch type closures: the latter being liable to pull out at the closure as a result of the shear forces between the lapped edges, or between the lapped edges and the patch, generated by the hoop stresses of recovery.
Known wraparound, heat recoverable fabric sleeves are described in EP-A-0116392 (RK178) and EP-A-0278707 (B137). The latter patent application describes a particular type of fabric design which is particularly applicable for heat recoverable articles having a recovery ratio of greater than 40% e.g. up to 75%, and which are advantageously closed by a rail and channel type closure that is able to withstand recovery forces up to 30N per 50 mm.